import pygame

class Ship():

    def __init__(self, ai_settings, screen):
        """初始化飞船并设置其初始位置"""
        self.screen = screen
        self.ai_settings = ai_settings

        #加载飞船图像并获取其外接矩形
        images_past = pygame.image.load('images/ship.bmp')
        self.image = pygame.transform.scale(images_past, (80, 80))
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        #将每艘新飞船放在屏幕底部中央
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
        self.center = float(self.rect.centerx)

        #移动标志
        self.moving_right = False
        self.moving_left = False


    def update(self):
        """根据移动标志调整飞船的位置"""
        if self.moving_right and self.center < self.screen_rect.right:
            self.center += self.ai_settings.ship_speed_factor
        if self.moving_left and self.center > 0:
            self.center -= self.ai_settings.ship_speed_factor
        self.rect.centerx = self.center
    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image, self.rect)


